The invention relates to a cassette having a box-shaped housing which comprises a bottom wall, an upper wall parallel to the bottom wall, and side walls which connect the bottom wall and the upper wall to one another, and which accommodates at least one reel which comprises a reel hub and at least one reel flange and which is adapted to take up a magnetic tape and which is drivable so as to be rotated about a reel axis which extends perpendicularly to the bottom wall and which is movable in a direction parallel to the reel axis between a rest position, in which latching means, arranged between the reel and the housing, lock the reel against rotation about the reel axis, and a drive position, in which the latching means are inoperative and the reel is drivable by means of a reel drive device with which it can be brought into driving engagement in a direction parallel to the reel axis through a passage provided in the bottom wall, and the reel, in the absence of the reel drive device, can be held in its rest position by means of a spring, which is arranged inside the housing and which urges the reel towards the bottom wall, and which is movable away from the bottom wall by means of the reel drive device from its rest position into its drive position.
Such a cassette of the type defined in the opening paragraph is known, for example, form the document U.S. Pat. No. 5,366,173A. In this known cassette the latching means for latching the reel against rotation are arranged in the area of the reel hub and are formed by a latching tab, which projects from the upper wall of the cassette housing in a direction parallel to the reel axis, and by a latching disc, which is rotationally coupled to the latching tab in a direction transverse to the reel axis and which is movable in a direction parallel to the reel axis between a latching position and a non-latching position. A pressure spring arranged between the upper wall of the cassette housing and the latching disc acts on the latching disc to urge the latching disc towards a reel hub ring, as a result of which--in the absence of a reel drive device in an apparatus adapted to cooperate with the known cassette and an actuating pin for moving the latching disc, which pin extends centrally through the reel drive device--the latching disc is held in its latching position, in which teeth provided on this disc are in mesh with corresponding teeth provided on the reel hub ring, thereby locking the reel against rotation about the reel axis. When the known cassette is loaded into an apparatus adapted to cooperate with the cassette the reel drive device and the actuating pin enter into engagement with the reel and the latching disc, upon which the reel is moved parallel to the reel axis away from the bottom wall of the cassette housing from its rest position into its drive position and the latching disc is moved parallel to the reel axis away from the bottom wall of the cassette housing from its latching position into its non-latching position against the force of the pressure spring. As a result of this, the reel is no longer locked against rotation and the reel can be driven rotationally by means of the reel drive device.
A problem of the known cassette is that the latching disc of the latching means--when the cassette is not in operation and situated outside an apparatus adapted to cooperate with the cassette--is readily and freely accessible through the passage provided to give access for the reel drive device and of the actuating pin, which may comparatively easily lead to an unintentional or inadvertent or inappropriate movement of the latching disc from its latching position into its non-latching position, which may subsequently result in an undesired rotation of the reel, which in its turn may result in the magnetic tape being wound unintentionally off the reel. Particularly when the cassette is subsequently put into operation again, such an unintentional unwinding of the magnetic tape may cause damage to the tape or also damage to parts of an apparatus which cooperate with the magnetic tape, which is obviously undesirable.